Hydraulic pneumatic driving tool



Aug. 14, 1962 J. K. KERSHAW HYDRAULIC PNEUMATIC DRIVING TOOL 2 Sheets-Sheet 1 Filed Sept. 29. 1959 INVENTOR. JOHN KNOX KERSHAW ll kl ATTORNEY Aug. 14, 1962 J. K. KERSHAW HYDRAULIC PNEUMATIC DRIVING TOOL 2 Sheets-Sheet 2 Filed Sept. 29, 1959 INVENTOR: JOHN KNOX KERSHAW BY- 5 j ATTORN EY United States Patent Gfitice 3,49,097 Patented Aug. 14, 1962 3,049,097 HYDRAULIC PNEUMATIC DRIVING TOOL John Knox Ker'shaw, 140 /2 Stockton St, Jacksonville, Fla. Filed Sept. 29, 1959, Ser. No. 843,095 11 Claims. (Cl. 12123) This invention relates to hydraulic pneumatic driving tool and is more particularly concerned with a portable impact driving tool employed for and a method of imparting reciprocable movement to a tool head or the like.

In the past portable trip hammers have been employed to break pavement and other hard surfaces. These trip hammers, however, are very noisy and highly-inei'licient devices using compressed air supplied through relatively small hoses to a piston, the air being supplied intermittently to force a piston downwardly. After the air has been employed for this purpose, it usually is discharged to the atmosphere.

In such an arrangement, it is usually necessary to station a large compressor driven by an internal combustion engine at a remote place to supply air to the relatively small tubes so that little dust is carried against the intake filter. Other devices such as compactors, and air drills, employ somewhat the same principal.

To overcome the disadvantages of the prior art and provide a highly versatile device, I have devised a driving tool which, briefly described, includes a cylinder and piston arrangement wherein compressed gas is supplied continuously to one side of the piston under essentially constant pressure conditions. Hydraulic liquid, under relatively higher pressure, is supplied to the other side of the piston intermittently to lift the piston against the force of the compressed gas. This hydraulic liquid is then quickly released through a large port so that a constant even force is applied to the piston throughout its stroke by the compressed air to drive the piston and its piston rod downwardly. Means are provided for controlling the flow of the hydraulic liquid into and out of the cylinder and means are provided for supplying and controlling the pressure of the compressed gas.

By such an arrangement, the efficiency of a hydraulic tool of this type may be raised from about to around 65% to 75% based upon the output of the prime mover.

Accordingly, it is an object of the present invention to provide an economical yet efiicient apparatus and method of imparting reciprocable movement to a tool.

Another object of the present invention is to provide a hydraulic pneumatic driving tool which is durable in structure, and yet less noisy than the prior art devices of the same class.

Another object of my invention is to provide a hydraulic pneumatic driving tool which will impart a substantially uniform pressure throughout the stroke of the tool head.

Another object of the present invention is to provide a hydraulic pneumatic driving tool which may be operated either as a single unit or with other similar units, being arranged in tandem.

Another object of my invention is to provide a hydraulic pneumatic driving tool which may achieve the results of a compressed air driven tool and yet have the efficiency of a liquid hydraulic system.

Another object of the present invention is to provide a hydraulic pneumatic driving tool which has a very high power to weight ratio.

Another object of my invention is to provide a hydraulic pneumatic driving tool which has a maximum impact with a minimum of horsepower expended.

Another object of my invention is to provide a hydraulic pneumatic driving tool which does not exhaust gases from the tool.

Another object of my invention is to provide a hydraulic driving tool which is suitable for use under water, in quicksand, and in all angles, the tool being free from sparks and hot gases which might cause ignition of volatile materials in the immediate vicinity.

Another object of the present invention is to provide a hydraulic driving tool in which the pressure of driving may be quickly and easily varied to suit varying demands;

Other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings wherein like characters of reference designate corresponding views and wherein:

FIG. 1 is a firagmentary side elevational view of a machine constructed in accordance with the present invention.

FIG. 2 is a cross sectional view taken along line 22 of FIG. 1.

FIG. 3 is a cross sectional view taken along line 33 in FIG. 2.

"FIG. 4 is a cross sectional view of a detail showing the gas controlled piston actuated pilot valve of the control system of the present invention.

FIG. 5 is a cross sectional view of a detail of the present invention, showing the gas relief valve for the control system of the present invention.

FIG. 6 is a cross sectional view of a detail showing the control valve of the control system of the present in vention.

FIG. 7 is a fragmentary front elevational view showing the arrangement of a device of the present invention in use as a pile driver or drill.

FIG. 8 is a fragmentary front elevational view showing the arrangement of the present invention in use as a trip hammer.

FIG. 9 is a cross sectional view of the flluid supply lines of the present invention.

'FIG. 10 is a schematic diagram showing the supplying of gas and liquid to the device of the present invention.

Referring now in detail to the embodiments chosen for the purpose of illustrating the present invention, numeral 10 denotes generally a hollow cylindrical casing. The casing 10 includes an upper body 11 and a lower body 12 joined at the central portion of casing 10. The upper body 11 is closed at its top to define an open ended cylindrical bore or chamber 13 which receives for reciprocation therein a piston 14 provided with a downwardly extending piston rod 15.

Centrally of upper body 11 and surrounding piston rod 15 is an annular, piston rod guide sleeve 16, the periphery of which is provided with external threads 17 which engage internal threads along the central inner wall of body 11 above the guide sleeve 16; the upper body 10 is provided with a plurality of exhaust ports 18 araoaaoov ranged radially around the central periphery of body 11 so as to communicate with chamber 13. An annular manifold 19 extending around the outer periphery of body 11 provides communication between all ports 18.

A control valve, best seen in FIG. 6, is mounted adjacent manifold 19 and communicate-s therewith through a port 20. In more detail, the control valve includes a hollow cylindrical housing 21 which is closed at both ends thereof, a central partition 22 separates housing 21 into an upper chamber 23 and a lower chamber 24, the lower chamber 24 communicating with port 20. In the upper chamber 23 is an air actuated piston 25 which is engaged by one end of a coil spring 26. The other end of the coil spring 26 engages a reaction plate 27 which is carried Within the upper end of chamber 23 by a set screw .28 projecting through the top of cylinder 21. By rotation of screw 28, the position of reaction plate 27 may be varied so as to vary the compressive force of spring 26 urging piston 25 to its lowermost position in chamber 23.

The piston 25 is provided with a connecting rod 29 which projects through the partition 22 into the chamber 24. The lower end of connecting rod 29 is provided with a piston 30 so positioned that when the piston 25 is urged to its lowermost position, the piston 30 closes port 20.

A high pressure hydraulic liquid supply conduit 31 communicates with the chamber 24, centrally thereof so as to supply hydraulic liquid, such as oil, to the chamber 24 above the piston 39. An oil supply port 32 is provided in housing 21 so as to connect chamber 24 and manifold 19 at a position above the port 20. The port 32 is in the same radial plane with conduit 31. A liquid return conduit 33 communicates with chamber 24 on a radial plane with port 20. ton 30 is in the position shown in FIGS. 2 and 6, hydraulic liquid is supplied through conduit 31 and chamber 24 to port 32 and thence to manifold, as the piston blocks communication between port and conduit 33. If, however, the piston is raised, the communication between conduit 31 and manifold 19 is blocked as the port 20 and conduit 33 are opened, permitting the hydraulic liquid from manifold 19 to discharge through port 20 and chamber 24 to discharge through conduit 33.

To raise the piston against the force of spring 26, compressed air is supplied through gas supply tube 34.

Thus, when the pis- Thus it is seen that when air, or any other gas for it will be discharged quickly. As shown schematically in FIG.-10, the hydraulic liquid is supplied from a sump tank 35 through a pump 36 to an accumulator 37 and thence, when required, to conduit 31. The return line, namely conduit 33, discharges the liquid back into the sump tank 35 whence it may be recirculated. Of course, it will be underestood that the sump tank 35, pump 36 and accumulator 37 may be located in a position remote from the driving tool.

Referring now to the gas reaction portion of the tool, compressed air, or any other gas, is supplied from a compresser 40 to an accumulator tank 41 and thence through a compressed gas conduit 42 to a regulator valve 43. From the regulator valve 43 the compressed gas under a predetermined pressure is introduced by means of a conduit 44 into the top of chamber 13 of body 10. Thus at all times during the operation of the tool, compressed gas acts upon the top of piston 14, tending to urge it downwardly. The amount of pressure so acting is determined by the setting of selector 45 of the regulator valve 4-3.

Between regulator valve and body 11, a blecder line 46 leads from the conduit 44 to a pilot valve, best seen in FIG. 4. The pilot valve includes a valve housing 47 mounted on the top of body 11. A valve actuating rod 48 projects through the packing 49 in housing 47 and terminates in a position to be engaged by piston 14 when it approaches the top of body 11. The other end of rod 48 is provided with a valve 50 which is urged by a spring 51 into a closed position on a seat provided in housing 47. A set screw 52 projecting through the housing 47 provides adjustment by which the compressive force of spring 51 may be varied.

When piston 14 engages and urges actuating rod 48 upwardly, the valve 50 is unseated or opened and therefore compressed air is supplied from conduit 44 through line 46 past valve 50 and into tube 53. Tube 53 is connccted to gas supply tube 34 through a T-connection. The other outlet of the T-connection is connected to a gas exhaust tube 54 which communicates with the gas exhaust valve best seen in FIG. 5.

The gas exhaust valve includes a housing 69 mounted on the side of body 11 at a position slightly above the guide sleeve 16. Within the housing 66 is a valve actuating ball 61, a portion of which projects within chamber 13 so as to be engaged by the piston 14 as it approaches its downmost position. Behind the ball 61 is a valve actuating rod 62, one end of which engages the ball 61. Rod 62 projects through the packing and is provided at its outer end with a valve 64 which is urged into a seated or closed condition by a spring 65 having a set screw 66. Thus, when the ball 61 is engaged by the piston 14, it is urged outwardly urging rod 62 and hence valve 64 outwardly away from its seat and thereby opening the exhaust valve whereby the compressed gas escapes from tube 54 past valve 64 and into tube 67 which communicates with the atmosphere. While I have shown the tube 67 as being relatively short, it will be understood that when the tool is used under water or in a place where it is undesirable to exhaust air, the tube may lead back to the source of compressed air.

It is now seen that when compressed air or other gas is supplied through regulator valve 43 and high pressure oil is supplied through conduit 31, the oil will pass through chamber 24 and port 32. into manifold 19 Where it is introduced through port 18 into chamber 13 to act against the bottom of piston 14, thereby raising it against the pressure of the compressed air in the top of chamber 13. When the piston approaches its upper-most position it engages rod 48 and opens the pilot valve, thereby introducing air via line 46 past valve 5% into tube 53 and then into tube 34 where it acts upon piston 25 to lift it against the pressure of spring 26. When valve 25 is lifted, it lifts piston 3t} to thereby close port 32 and open port 21 to conduit 33.

When this occurs, the compressed air from conduit 44 acts on piston 14 urging it downwardly and pushing the oil through ports 18 into manifold 19 and thence through port 20 and chamber 24 into line 33. The control valve comprising pistons 25 and 30 remains up even though the piston 14 no longer engages rod 48 and spring 51 reseats valve 53, because compressed air still acts upon piston 25.

As the piston 14 approaches the bottom of its stroke, it engages ball 61 and thereby opens the gas exhaust valve which permits the air to be bled from the chamber 23 through tube 34 and 54 past the opened valve 64 and through tube 67. This permits spring 26 to return the control valve to its original position where oil is again introduced into chamber 24 from conduit 31 and the cycle is repeated. Thus it is seen that the piston rod 15 is reciprocated.

At the lower end of body 11, external threads 70 are provided which engage internal threads at the upper end of lower housing 12. The lower housing 12 is provided with an internal hexagonal bore 71 which is concentric with the chamber 13 of upper housing 11. Within the bore is a slideable hexagonal anvil 72 which is adapted to be struck by the lower end of the piston rod 15 upon each reciprocation. The lower end of the anvil 72 is provided with a center bore 73 adapted to receive an end of a suitable tool head 75, the end of the tool head 75 projecting through an opening 76 of smaller diameter than bore 71 in lower body 12. A suitable removable clip 77 retains the tool head 75 in place, there being an enlarged portion 78 on the tool so that it will not pass downwardly through the clip 77.

Thus it is seen that the momentum of the piston 14 will be imparted to the tool head 75 and thence to the object 300.

Referring now to FIG. 7, if it is desired to employ my machine for driving a pipe, such as pipe 99, into the ground such as when drilling a well, a frame having vertical standards 100 is employed. The standards 100 are joined at their upper ends by cross bars, such as cross bar 101, so as to provide a rigid structure wherein the standards 1100 provide vertical guide rails for retaining the casing 10 in vertical position. Casing 10 is provided with one or a plurality of transverse skid bars 10?. secured to casing 10 and extending between adjacent standards 100. The ends of the skid bars 102 are provided with brackets 103 which extend around the inner edge of standards 1.00 to permit vertical reciprocation of the skid bars 102 carrying casing 10. Thus casing 10 is independently slidable along standards 100.

The upper end of casing 10 is provided with a pulley 1.04 and a cable 105, secured by eyelet 106 to cnoss bar 101. The cable 105 loops around the pulley 104 to provide a means by which the casing 10 may be raised or lowered. In the embodiment here illustrated, a relatively Wide flat auxiliary anvil 175 is substituted for the tool head 75. The bottom portion 176 of anvil 175 is relatively wide and sits on the upper end of pipe 99. At the outer edges of the bottom portion 176 of auxiliary anvil 175 there are provided brackets 177, which are similar to brackets 103 and slidably engage the standards 100. Thus, the auxiliary anvil is slidable with casing 10 along standards 100.

Conduits for the supply of gas and liquids, such as conduits 31 and 44, are retained within the larger conduit 33' such as shown in FIG. 9. To provide a supply of air to chamber 13, a tube 107 leads from conduit 44 through the conduit 33 to the top of casing 10.

Referring now to FIG. 8, if the device of the present invention were to be employed as a portable trip hammer, suitable handles 200, 200 are provided on the ends of a handle bar 201 secured in a suitable manner to cars ing 10. Handle 200' is provided with a sleeve 202 having a helical groove 203 so that upon rotation of handle 200" the position of the groove 203 may be changed. As illustrated in FIG. 8, an end of a control rod 245 rides in the groove 203 so that it may be moved laterally upon rotation of handle 200. This control rod 245, in turn, is connected to a regulator valve 243 connected between tube 107 and the top of casing 10 so as to control the pressure of air acting upon the upper surface of piston 14 of FIG. 2.

In the device of FIG. 8, a pointed tool head 275 is employed for say breaking concrete, or the like. By controlling handle 200 the air or gas pressure on piston 14- may be varied from no pressure up to any desired pressure. At no gas pressure, it will be understood that the pilot valve, even though open, supplies no air or insufficient air to actuate the control valve of housing 21 and hence the device for all practical purposes is deactuated. If, however, the handle 200 is rotated sufiiciently for the air pressure acting on the lower portion of piston to actuate the piston 25, the device commences to operate. Additional rotation of handle 2-00 increases the air pressure and hence increases the force exerted by the piston rod 15 in its downward travel.

The efliciency of the present device as compared with the prior art may best be illustrated by the fact that prior art multiple tampers weigh about 60,000 pounds and use about 600 cubic feet of air at p.s.i. from a 300 horsepower prime mover to operate 16 tampers which deliver about 16 horsepower of driving force as a total. On the other hand, my tests indicate that the present machine when substituted for the tampers of the above ma chine would require only a 40 horsepower prime mover and the total weight Would only be 10,000 pounds.

It will be obvious to those skilled in the art that many variations may be made in the embodiments here chosen for the purpose of illustrating the present invention without departing from the scope thereof as defined by the appended claims.

I claim:

1. An impact driving tool comprising a casing having a chamber and port means at one end communicating with said chamber, a piston within said chamber, means connected to the other end of said casing and communicating with said chamber for introducing gas under pressure against one side of said piston, a manifold connected "to said casing and communicating with said port means, valve means connected to said manifold means, a high pressure liquid supply conduit connected to said valve means for introducing when said valve means is in one position, liquid under pressure through said valve means into said manifold and thence through said port means and into said chamber to act against the other side of said piston for moving said piston in one direction against the pressure exerted by said gas, a liquid return conduit connected to said valve means for rapidly releasing said fluid from acting against said other side of. said piston when said valve means is in another position to permit said gas to urge said piston in the other direction, means actuated by the position of said piston for actuating said valve means to impart continuous reciprocating motion to said piston by the successive introducing into and releasing of liquid from said chamber and momentum transfer means for transferring the momentum of movement of said piston in said other direction to an ob ject of work as an impact.

2. In an impact driving tool, a cylinder, a piston reciprocatable within said cylinder, a piston rod extending from one surface of said piston outwardly of said cylinder, an anvil engageable by said piston rod as said piston rod approaches the end of its stroke in one direction, means for introducing compressed gas against the other surface of said piston for urging said piston rod toward said anvil and into engagement therewith and means for urging said piston against the force of said compressed gas in the other direction away from said anvil, and means controlled by the position of said piston for rapidly releasing said piston at the end of its stroke in said other direction, whereby the force of said compressed gas urges said piston in said one direction and against said anvil.

3. In an impact driving tool, a cylinder, a reciprocatable piston within said cylinder, a piston rod connected to and movable with said piston, said piston rod extending from said cylinder, an anvil engageable by the end of said piston rod as said piston and piston rod approach r the one end of their stroke, conduit means for introducing gas under pressure from a source of gas under pressure into said cylinder to urge said piston into said one end of its stroke, means for introducing liquid under pressure into said cylinder to urge said piston and piston rod toward the other end of their stroke, and means actuated by said piston as said piston approaches the end of its travel toward said other end of its stroke for releasing said liquid from said cylinder whereby said gas urges said piston toward said anvil.

4. In an impact driving tool, a cylinder, a reciprospaaosv catable piston within said cylinder, a piston rod con nected to and movable with said piston, said piston rod extending from said cylinder, an anvil engageable by the end of said piston rod as said piston and piston rod approach the one end of their stroke, means for introducing gas under pressure into said cylinder to urge said piston into said one end of its stroke, means for introducing liquid under pressure into said cylinder to urge said piston and piston rod toward the other end of their stroke, means actuated by said piston as said piston approaches the end of its travel toward said other end of its stroke for releasing said liquid from said cylinder whereby said gas urges said piston toward said anvil, and a removable tool head asosciated with said anvil for imparting work to an object, said means for releasing said liquid including a control valve and pilot means engalgeable by said piston for controlling said control valve.

5. An impact driving tool comprising a hollow casing, an anvil movably retained at one end of said casing, a reciprocatable piston in the other end of said casing, a piston rod connected to said piston and adapted to engage said anvil as said piston moves toward said anvil, a partition in said casing for confining said piston within a chamber, conduit means for introducing compressed gas from a remote source of gas under pressure into said chamber for constantly urging said piston toward said anvil, a pressure regulator in said conduit means, conduit means connected to said casing and communicating with said chamber for introducing liquid under pressure into said chamber against said piston to urge said piston away from said anvil, and for releasing said liquid from said chamber to permit said compressed air to urge said piston toward said anvil, control means connected to said conduit means for controlling the ingress and egress of said liquid to and from said chamber, and actuation means for controlling said control means in response to the position of said piston in said chamber.

6. An impact driving tool comprising a hollow casing, an anvil movably retained at one end of said casing, a reciprocatable piston in the other end of said casing, a piston rod connected to said piston and adapted to engage said anvil as said piston moves toward said anvil, a partition in said casing for confining said piston within a chamber, means for introducing compressed gas into said chamber for constantly urging said piston toward said anvil, conduit means connected to said casing and communicating with said chamber for introducing liquid under pressure into said chamber against said piston to urge said piston away from said anvil, and for releasing said liquid from said chamber to permit said compressed air to urge said piston toward said anvil, control means connected to said conduit means for controlling the ingress and egress of said liquid to and from said chamber, actuation means for controlling said control means in response to the position of said piston in said chamber, said control means including a control valve actuated by said compressed gas and said actuation means including a pilot valve actuated to admit said gas to said control valve as said piston approaches an end of its stroke, and means actuated when said piston approaches the other end of its stroke for releasing said compressed gas from said control valve.

7. An impact driving tool comprising a hollow casing, an anvil movably retained at one end of said casing, 21 reciprocatable piston in the other end of said casing, a piston rod connected to said piston and adapted to engage said anvil as said piston moves toward said anvil, a partition in said casing for confining said piston within a chamber, means for introducing compressed gas into said chamber for constantly urging said piston toward said anvil, conduit means connected to said casing and communicating with said chamber for introducing liquid under pressure into said chamber against said piston to urge said piston away from said anvil, and for releasing .said liquid from said chamber to permit said compressed air to urge said piston toward said anvil, control means connected to said conduit means for controlling the ingress and egress of said liquid to and from said chamber, actuation means for controlling said control means in response to the position of said piston in said chamber, said control means including a control valve actuated by said compressed gas and said actuation means including a pilot valve actuated to admit said gas to said control valve as said piston approaches an end of its stroke, and means actuated when said piston approaches the other end of its stroke for releasing said compressed gas from said control valve, said conduit means including a liquid supply conduit of relatively small size and a liquid discharge conduit of relatively large size.

8. An impact driving tool comprising a hollow casing, an anvil movably retained at one end of said casing, a reciprocatable piston in the other end of said casing, a piston rod connected to said piston and adapted to engage said anvil as said piston moves toward said anvil, a partition in said casing for confining said piston within a chamber, means for introducing compressed gas into said chamber for constantly urging said piston toward said anvil, conduit means connected to said casing and communicating with said chamber for introducing liquid under pressure into said chamber against said piston to urge said piston away from said anvil, and for releasing said liquid from said chamber to permit said compressed air to urge said piston toward said anvil, control means connected to said conduit means for controlling the ingress and egress of said liquid to and from said chamber, actuation means for controlling said control means in response to the position of said piston in said chamber, said control means including a control valve actuated by said compressed gas and said actuation means including a pilot valve actuated to admit said gas to said control valve as said piston approaches an end of its stroke, means actuated when said piston approaches the other end of its stroke for releasing said compressed gas from said control valve, said conduit means including a liquid supply conduit of relatively small size and a liquid discharge conduit of relatively large size, and including means 'for adjusting the pressure of said compressed gas.

9. Method of imparting an impact to an object which comprises arranging a tool head or contact with said object, constantly urging a mass into engagement with said tool head by even pressure against said mass in the direction of said tool head, cyclically overcoming said even pressure against said mass to urge said mass away from said tool head and releasing said mass after the same has been moved a predetermined distance away from said tool head whereby said even pressure returns said mass to said tool head upon each cycle to impart the momentum of said mass to said tool head.

10. Method of imparting an impact to an object which comprises arranging a tool head for contact with said object, confining a gas under pressure, directing said gas against a mass to constantly urge said mass toward said tool head and into engagement with said tool head, confining a liquid, introducing said liquid under pressure against said mass to overcome the pressure of said gas, urging said mass against said pressure of said gas by said liquid pressure away from said tool head a predetermined distance, releasing said liquid as said mass approaches said predetermined distance whereby the force of said gas under pressure urges said mass toward and into engagement with said tool head, and introducing additional liquid under pressure for urging of said mass away from said tool head after each engagement of said mass with said tool head and repeating the releasing of said liquid after said mass has been moved a predetermined distance whereby said mass successively engages said tool head.

11. The method defined in claim 10 including the step of diverting a portion of the compressed air to actuate the releasing of said liquid during each cycle of the mass as said mass approaches said predetermined distance away from said tool head.

References Cited in the file of this patent UNITED STATES PATENTS Re. 2,461 James Jan. 15, 1867 223,464 Bailey Jan. 13, 1880 580,154 Bullock Apr. 6, 1897 

